This paper investigates reasons for the uneasy relationship between Systemic Functional Linguistics (SFL) and the discipline of psychology. It proposes a role for psychological data in SFL, and describes a case study that attempts to combine the methodology of psychology with SFL';s discourse-based approach to language. The case study examines the interpretation of the data obtained from a psychological approach to the SFL puzzle of information structure in written English, and provides evidence to suggest that the SFL notion of information structure has psychological validity.